1. Field of the Invention
The present invention relates to a pump unit used as a hydraulic source for a pair of hydraulic motor units allocated and arranged on both sides in a width direction of a vehicle so as to drive a pair of left and right driving axles, and to a working vehicle equipped with the pump unit.
2. Related Art
In a working vehicle, it is desirable to have a free space at a central portion in a width direction of the vehicle without enlarging the entire vehicle size. That is, by forming the free space at the central portion in the width direction of the vehicle, the free space can be used as an installation space for a mid-mount mower, used as a center discharger path and, further, used as an installation space for a mower lifting cylinder, thus enhancing the degree of freedom of design of the working vehicle.
For example, in U.S. Pat. Nos. 4,395,865 and 5,809,756 (hereinafter, referred to as cited references 1 and 2, respectively), there is proposed a working vehicle comprising a hydraulic pump unit operatively connected to a driving source, and a pair of hydraulic motor units allocated and arranged on both sides in a width direction of a vehicle so as to drive a pair of right and left driving axles, wherein the hydraulic pump unit and the pair of hydraulic motor units are fluidly connected to each other via a conduit.
The conventional working vehicle having the above configuration is effective in preventing a traveling-system transmission mechanism to be interposed between the pair of driving axles, but is ineffective with regard to the following points.
That is, in the working vehicle, a PTO-system transmission mechanism for transmitting power from the driving source to a working machine must be arranged in addition to the traveling-system transmission mechanism for transmitting power from the driving source to the pair of driving axles.
Therefore, according to the above working vehicle, not only the traveling-system transmission mechanism, but the PTO-system transmission mechanism must also be considered in order to secure a free space at the central portion in the width direction of the vehicle.
The conventional working vehicle prevents the traveling-system transmission mechanism from being positioned at the central portion in the width direction of the vehicle due to the above configuration, but the PTO-system transmission mechanism is not taken into consideration.
The present invention has been made in view of the above conventional art, and it is an object of the present invention to provide a pump unit applicable to a working vehicle equipped with a working machine. Herein, the pump unit forms a traveling-system transmission mechanism in cooperation with a pair of hydraulic motor units allocated and arranged on both sides in a width direction of a vehicle and, also, forms a PTO-system transmission mechanism for outputting rotational power toward the working machine. In addition, the pump unit can prevent both the traveling-system transmission mechanism and the PTO-system transmission mechanism from being positioned at a central portion in the width direction of the vehicle as much as possible.
It is another object of the present invention to provide a working vehicle capable of preventing both the traveling-system transmission mechanism and the PTO-system transmission mechanism from being positioned at the central portion in the width direction of the vehicle as much as possible.